On the Asymmetry of the Tropical Pacific Thermocline Fluctuation Associated With ENSO Recharge and Discharge

The El Nino/Southern Oscillation (ENSO) plays a crucial role in a successful climate prediction at seasonal-interannual time scales. One of the challenges of forecasting the ENSO is from the non-cyclical feature, which is linked to the ocean heat discharge and recharge processes of the equatorial Pacific. We note that there are appreciable differences in both the intensities and spatial patterns associated with preceding thermocline fluctuation in the tropical Pacific between the recharge and discharge phases of ENSO. Preceding thermocline anomalies in the western and central deep tropical Pacific contribute to the recharge phase of ENSO, while preceding thermocline anomalies in the western (eastern) tropical Pacific have a positive (negative) contribution to the discharge phase of ENSO. The contrastive connections with the preceding thermocline fluctuation are mainly due to the asymmetric wind stress anomalies associated with El Nino and La Nina.

Automated summary

The El Nino/Southern Oscillation (ENSO) plays a crucial role in successful climate prediction at seasonal-interannual time scales. Differences in intensities and spatial patterns associated with preceding thermocline fluctuation in the equatorial Pacific during the recharge and discharge phases of ENSO can be attributed to asymmetric wind stress anomalies related to El Nino and La Nina.